Haloperidol, described in U.S. Pat. No. 3,438,991, is a well-known neuroleptic agent used for treating psychoses, such as schizophrenia. Use of haloperidol causes side effects including acute extrapyramidal syndrome (EPS) which is usually seen soon after antipsychotic therapy is begun as well as the more chronic dystonic syndrome known as tardive dyskinesia which sometimes emerges during long-term antipsychotic use.
Attempts at reducing the side effects of haloperidol have been reported. U.S. Pat. No. 3,978,216 describes the use of a gabergic compound administered prior to or with a neuroleptic agent to reduce tardive dyskinesia. Benzodiazepines have been reported to be effective in the reduction of serum prolactin when used with haloperidol, U.S. Pat. No. 4,316,897. Desipramine and imipramine have been reported to reduce Parkinson-like symptoms in the treatment of schizophrenia with haloperidol in U.S. Pat. No.3,505,451.
The present invention has for its object a method of treating psychoses, e.g., schizophrenia, and reducing the side effects of such treatment, such as acute extrapyramidal syndrome and tardive dyskinesia by administering a novel adenosine derivative prior to or concomitant with haloperidol therapy.
Another object of the present invention is a new pharmaceutical composition comprising effective amounts of haloperidol and a novel adenosine derivative with a carrier to treat schizophrenia with reduced side effects. The presence of the novel adenosine compound not only reduces the chance of tardive dyskinesia but increases the efficacy of haloperidol thereby requiring lower doses of haloperidol in the therapy.